The New York State Senate was dominated by the Republican Party for much of the 20th century. Between World War II and the turn of the 21st century, the Democratic Party only controlled the upper house for one year. Following the 1964 presidential election, the Democrats took control of the Senate in 1965; however, the Republicans quickly regained a Senate majority in special elections later that year.

The Senate's apportionment has traditionally favored upstate New York due to the New York Constitution's original method of giving each county—even sparsely populated counties—at least one senator (a practice that mirrored the equal number of United States Senators elected from each state).[2] This apportionment method changed with Baker v. Carr (1962) and Reynolds v. Sims (1964), in which the U.S. Supreme Court ruled that a "one man, one vote" system of state legislative apportionment is constitutionally required. Since then, in redistricting, the Senate has traditionally over-represented upstate New York in exchange for the Assembly over-representing downstate (each legislative district is allowed up to 5% deviation from the average district population; the Legislature systematically uses this leeway to create less populous Senate districts upstate and more populous ones downstate, and vice versa in the Assembly).

State Senate seats in New York City are typically held by Democrats, while Senate seats outside New York City are typically held by Republicans. As of the start of the 2018 session, enrolled Republicans held only two seats in New York City: District 22 (Sen. Marty Golden, R-Brooklyn) and District 24 (Sen. Andrew Lanza, R-Staten Island). However, enrolled Democrats held only three seats north of Westchester County: Districts 44 (Sen. Neil Breslin), 53 (Sen. David Valesky), and 63 (Sen. Tim Kennedy). Furthermore, enrolled Democrats held only two of the nine Long Island Senate seats: District 8 (Sen. John Brooks) and District 9 (Sen. Todd Kaminsky). Eight of the enrolled Democrats were members of the Independent Democratic Conference, and another (Sen. Simcha Felder, D-Brooklyn[3]) caucused with the Republicans after being elected on the Democratic, Republican, and Conservative Party lines.[4]

In April 2018, The Wall Street Journal described the State Senate as the "last bastion of power" of the Republican Party in the State of New York.[5] On Election Day 2018, the Democratic Party gained several State Senate seats. The following day, The New York Times wrote that the Democrats had "decisively evict[ed] Republicans from running the State Senate, which they [had] controlled for all but three years since World War II."[6]

Democrats won 32 of 62 seats in New York's upper chamber in the 2008 general election on November 4, capturing the majority for the first time in more than four decades.[19][20] Previously, the Republicans had held the chamber for all but one year from 1939 to 2008, even as New York turned almost solidly Democratic at all levels.

However, a power struggle emerged before the new term began. Four Democratic senators—Rubén Díaz Sr. (Bronx), Carl Kruger (Brooklyn), Pedro Espada, Jr. (Bronx), and Hiram Monserrate (Queens)—immediately refused to caucus with their party.[21] The self-named "Gang of Four" refused to back Malcolm Smith (Queens) as the chamber's majority leader and sought concessions.[22] Monserrate soon rejoined the caucus after reaching an agreement with Smith that reportedly included the chairmanship of the Consumer Affairs Committee.[23] The remaining "Gang of Three" reached an initial compromise in early December that collapsed within a week,[24] but was ultimately resolved[25] with Smith becoming majority leader.[26]

At the beginning of the 2009–2010 legislative session, there were 32 Democrats and 30 Republicans in the Senate. On June 8, 2009, then-Senators Hiram Monserrate and Pedro Espada, Jr.--both Democrats—voted with the 30 Republican members to install Senate Republican Leader Dean Skelos (R-Rockville Centre) as the new majority leader of the Senate, replacing Democratic Senate Majority Leader Malcolm Smith.[27][28] The Associated Press described the vote as a "parliamentary coup". The move came after Republican whip Tom Libous introduced a surprise resolution to vacate the chair and replace Smith as temporary president and majority leader. In an effort to stop the vote, Democratic whip Jeff Klein (Bronx) unilaterally moved to recess, and Smith had the lights and Internet cut off; however, they were unable to prevent the vote from being held. In accordance with a prearranged deal, Espada was elected temporary president and acting lieutenant governor while Skelos was elected majority leader.[29]

Following the coup, Senate Democrats voted for John Sampson (D-Brooklyn) to replace Smith as Democratic Leader. On June 14, Monserrate declared that he would once again caucus with the Democrats. This development meant that the Senate was evenly split, 31–31, between the Republican Conference and the Democratic Conference. Due to a vacancy in the office of the Lieutenant Governor, there was no way to break the deadlock.[30]

Between June 8 and the end of the coup on July 9, the Senate did not conduct any official business.[31] According to The New York Times, Espada's power play "threw the Senate into turmoil and hobbled the state government, making the body a national laughingstock as the feuding factions shouted and gaveled over each other in simultaneous legislative sessions."[32] The coup also led to litigation.[33]

On July 9, 2009, the coup ended. Espada rejoined the Senate Democratic Conference after reaching a deal in which he would be named Senate Majority Leader,[34] Sampson would remain Senate Democratic Leader, and Smith would be Temporary President of the Senate during a "transition period" after which Sampson would ascend to the Temporary Presidency.[35] On February 9, 2010, the Senate voted to expel Monserrate from the Senate following a misdemeanor domestic violence conviction.[36] Espada was defeated in a September 2010 primary election[37] in which the Democratic Party backed his challenger, Gustavo Rivera.

Just before the new legislative session convened in January 2011, four Democrats, led by former Democratic whip Jeff Klein, broke away from the main Democratic Conference to form an Independent Democratic Conference (IDC). Klein said that he and his three colleagues, Diane Savino, David Carlucci and David Valesky could no longer support the leadership of Senate Democratic Leader John Sampson.[47]

In March 2011, "Gang of Four" member Senator Carl Kruger surrendered to bribery charges. He later pleaded guilty to those charges in December of 2011.[48]

Following the 2010 census, New York redistricted the Senate, expanding it from 62 to 63 seats effective in January 2013. When all election night results were tabulated on November 6, 2012, Democrats held a total of 33 seats for a three-seat majority. Democrats gained seats in Senate Districts 17 (where Democrat Simcha Felder defeated Republican incumbent David Storobin), 41 (where Terry Gipson defeated Republican incumbent Stephen Saland), and 55 (where Ted O'Brien defeated Sean Hanna), and won an election in the newly-created Senate District 46.[49][50][51] However, on December 4, 2012, it was announced that Senate Republicans had reached a power-sharing deal with the four-member Independent Democratic Conference (IDC). Under their power-sharing arrangement, the IDC and the Senate Republicans to "jointly decide what bills [would] reach the Senate floor each day of the session", would "dole out committee assignments", would "have the power to make appointments to state and local boards", and would "share negotiations over the state budget".[52] Sens. Klein and Skelos also agreed that the title of Senate President would shift back and forth between the two of them every two weeks.[52]

Together, the Senate Republicans and the IDC held enough seats to form a governing majority; that majority was augmented when freshman Sen. Simcha Felder of Brooklyn, a Democrat, chose to join the Senate Republican Conference.[53] Also, former Democratic Senate Majority Leader Malcolm Smith joined the Independent Democrats,[54] only to be expelled from the conference in April 2013 due to a scandal in which Smith attempted to bribe the Republican Party chairs in New York City for a Wilson Pakula to run in the upcoming New York City mayoral election.[55] (The previous Senate Minority Leader, Sen. John L. Sampson, was expelled from his conference on May 6, 2013 following his arrest on embezzlement charges. Sampson was later convicted for making false statements to federal agents in relation to the initial embezzlement case.[56])

Senate District 46 was embroiled in controversy following the 2012 election. Republican George Amedore was sworn in to the State Senate following the election. However, after a recount was completed, Amedore lost by 18 votes to Democrat Cecilia Tkaczyk; this made Amedore the shortest-tenured senator in modern New York history.[57][58] Amedore would eventually win a rematch with Tkaczyk in 2014.[59]

In February 2014, Tony Avella joined the Independent Democratic Conference.[60] Later that year, the IDC announced that it would end its political alliance with the Republicans and create a new one with the Senate Democratic Conference, citing a need "to fight for the core Democratic policies that are left undone."[61] In the 2014 elections, Senate Republicans retook an outright majority in the Senate,[62] The election results meant that Klein lost his position as co-leader, with Skelos taking over as the Senate Majority Leader and Temporary President of the Senate and regaining sole control over which bills would reach the Senate floor.[52][63][64] The IDC members decided to remain allied with the Republicans in the 2015 legislative session[63][65] despite their conference's diminished role.[52]

On May 4, 2015, U.S. AttorneyPreet Bharara announced the arrest of Senate Majority Leader Dean Skelos (along with his son, Adam Skelos) and the arrest of Assembly Speaker Sheldon Silver.[66] Within days, Skelos announced that he was stepping down as leader of the Republican Caucus and as Majority Leader. Senator John Flanagan, of Suffolk County, became the new Majority Leader, and the first Majority Leader from Suffolk County.[67] After Skelos was convicted in December 2015, his seat was declared vacant, with a special election to be held on the presidential primary of 2016.[68][69] The special election was won by Democrat Todd Kaminsky, resulting in the Democratic Party having a numerical 32-31 advantage over the Republicans in the State Senate. Despite this, Senator Felder and the members of the IDC chose to remain in coalition with the Republican majority.

Late in 2016, Senator Jesse Hamilton announced his intention to join the IDC if re-elected.[70] The IDC aided Hamilton in his first election in 2014, which had resulted in speculation he would eventually join the conference.[71]

After all 2016 election results were announced, Senate Republicans lost one seat on Long Island and gained an upstate seat in Buffalo. On Long Island, freshman Sen. Michael Venditto was defeated in a close race by Democrat John Brooks.[72] In Buffalo, the open seat vacated by Democratic Sen. Mark Panepinto (who did not seek re-election) was won by Republican Erie County Clerk Chris Jacobs. Sen. Simcha Felder, who tied for most conservative member of the Senate according to the Conservative Party in 2016,[73] announced that he would continue to caucus with the GOP; Felder's move ensured that the Republicans would retain control of the Senate by a margin of 32–31.[74] Newly elected Democratic Sen. Marisol Alcantara also announced that she would join the IDC, after Klein assisted her campaign.[75][76]

Liberal groups in New York State, including the Working Families Party, called on the governor to intervene and pressure Sen. Felder, the IDC, and the Senate Democratic Conference to unite to make New York a united one-party government in opposition to President-electDonald Trump's incoming administration. Klein criticized those groups along with Minority Leader Andrea Stewart-Cousins for lack of outreach as well as for calling on the governor to intervene in a separate branch of government. On January 2, 2017, Senate Majority Leader Flanagan and Senate IDC Leader Klein announced the continuation of their coalition. Klein, in a statement to the press, opined that the coalition allowed for the passage of bipartisan legislation and the consideration of pragmatic, progressive ideas.[77] The Republicans retained Senate control with 32 votes, including every Senator elected as a Republican and Sen. Felder.[78] In late January 2017, Senator Jose Peralta announced that he was joining the IDC, expanding the IDC to 8 members, the Republican-IDC-Felder coalition to 40 members, and reducing the Democratic conference to 23 members.[79]

On April 4, 2018, the IDC announced that it would dissolve, that its members would rejoin the Senate Democratic Conference, that Stewart-Cousins would continue as Senate Democratic Leader, and that Sen. Klein would become the Deputy Democratic Conference Leader.[80] The announcement followed a meeting called by Governor Andrew Cuomo at which Cuomo requested that the IDC reunite with the Senate Democratic Conference.[81] On April 16, the IDC was dissolved.[82] After the IDC dissolved, the Senate Democratic Conference contained 29 Members, the Senate Republican Conference contained 32 Members (including Sen. Felder), and there were two vacant Senate seats.[83]
After two April 24, 2018 special elections were won by Democrats, the Democrats gained a 32–31 numerical Senate majority; however, Felder continued to caucus with the Republicans, allowing them to maintain a 32–31 majority instead.[84]

On November 6, 2018, the Democratic Party won a sizeable majority in the State Senate. Democratic challengers defeated incumbent Republican Sens. Carl Marcellino and Elaine Phillips and won races in three districts (Districts Three, 39, and 42, respectively) in which Republican incumbents had not sought re-election.[96][97] As of November 8, 2018, there were four other close Senate races in which neither candidate had conceded defeat.[98]

The Senate is headed by its President, a post held ex officio by the Lieutenant Governor. The Senate President has a casting vote in the event of a tie, but otherwise may not vote. More often, the Senate is presided over by the Temporary President, a post which is normally also held by the Majority Leader.

The Senate has one additional officer outside those who are elected by the people. The Secretary of the Senate is a post that is chosen by a majority vote of the senators, and does not have voting power (he/she is allowed, though officially discouraged, from discussing and negotiating legislative matters). The Secretary of the Senate is responsible for administering the Senate's office space, overseeing the handling of bills and the oversight of the sergeants-at-arms and the stenographer. The position is currently held by Frank Patience, who was elected to a two-year position in January 2011.[99]

^Sen. Felder has been elected on the Democratic, Republican and Conservative Party lines (as of the 2016 election) and has caucused with the Republicans since his first election, but he is a registered Democrat.